The present invention relates generally to mechanisms for interconnecting electrical leads and electrical medical devices; and more particularly, to systems and methods of interconnecting implantable electrical leads and implantable medical electrical devices such as pacemakers, nerve stimulators, implantable defibrillators, implantable monitors, and so forth.
As implantable electrical devices have increased in their complexity, there has been an increasing variety of electrical lead systems developed for use in conjunction with these devices. Nowhere is this more apparent than in the context of implantable cardioverter/defibrillators, which may include three, four, five, or more electrodes located on various numbers of implantable electrical leads. The leads themselves may carry one, two, three, or more electrodes, and may employ a variety of different electrical connector configurations and types. As a result, manufacturers of implantable cardioverter/defibrillators have had to produce their products with a variety of connector block configurations, capable of use with different lead systems. For example, Medtronic, Inc. presently manufactures implantable cardioverter/defibrillators with four basic connector designs, designated configurations xe2x80x9cBxe2x80x9d, xe2x80x9cCxe2x80x9d, xe2x80x9cDxe2x80x9d, and xe2x80x9cExe2x80x9d. The xe2x80x9cBxe2x80x9d configuration includes three 6.5 mm connector bores for receiving high voltage electrical lead connectors of the type used to couple to cardioversion/defibrillation electrodes and one 3.2 mm in-line electrical connector bore compatible with the IS-1 connector standard for receiving an IS-1 electrical lead connector of the type generally used to couple to cardiac pacing and sensing electrodes. The xe2x80x9cCxe2x80x9d configuration includes a single 3.2 mm connector bore conforming to the DF-1 standard for receiving high voltage electrical lead connectors used to couple to cardioversion/defibrillation electrodes. This configuration also includes a single IS-1 connector bore. The xe2x80x9cDxe2x80x9d configuration includes three DF-1 connector bores and one IS-1 connector bore. The xe2x80x9cExe2x80x9d configuration includes two 6.5 mm connector bores and two 5 mm connector bores for receiving electrical lead connectors used to couple to individual cardiac pacing and sensing electrodes.
As is apparent from the above discussion, multiple connectors block types are necessitated both by the use of multiple connector standards, and also because of the desire to connect a varying number of lead systems to a given device. The situation is complicated even further by the use of non-standard connector systems. For example, it has been increasingly common to utilize small-diameter guide catheters to deliver leads having a diameter of 7 French or less to a desired implant site. After lead placement is completed, the catheter must be withdrawn from the body. However, if the catheter has a small inner diameter, the inner lumen of the catheter cannot accommodate a standard-size lead connector such as one conforming to the IS-1 standard. In this situation, the catheter must be split or slit into two portions. Such slittable or splittable catheters are more expensive to manufacture, and require the additional slitting step to remove. To remedy this problem, the lead may instead include a small-diameter, non-standard connector that easily fits within the catheter lumen, allowing the catheter to be readily withdrawn from the body. This non-standard connector has the drawback of necessitating the use of an even larger number of connector block configurations.
One way to solve the problem is to provide adapters that adapt one lead connector type to a different connector type on the device. These adapters may take the form of a relatively short lead which at one end has a connector assembly which may be inserted into one or more bores on the connector block on the implantable device and at the other end has one or more connector bores capable of receiving the connector assembly or assemblies on the electrical leads to be used with the device. These adapters are bulky and add substantially to the size of the pocket in which the device is to be implanted. In addition, they tend to require a number of additional steps to be performed by the physician in order to couple the leads to the implanted device, and are thus seen as undesirable generally. Such adapters are disclosed in U.S. Pat. No. 5,000,177, issued to Hoffmann, and U.S. Pat. No. 5,328,442, issued to Levine. Some adapters, such as disclosed in U.S. Pat. Nos. 5,050,602 issued to Osypka and 5,060,649 issued to Hocherl et al. even required removal of the connector assembly of the lead as part of the connection process.
Another approach to resolving lead/device incompatibility problems involves use of an up-sizing adapter. An up-sizing adapter is used to convert a smaller-diameter standard or non-standard lead connector to a larger-sized device connector. This is particularly useful when dealing with leads having smaller connectors for use with non-splittable guide catheters. As discussed above, a smaller lead connector allows guide catheters to be easily withdrawn over the lead proximal end after the implant procedure is completed. After the guide catheter has been removed from the body, the up-sizing adapter may be connected to allow the lead to be coupled to a device.
One example of an up-sizing adapter is shown in U.S. Pat. No. 5,007,864, issued to Stutz Jr. This patent discloses an adapter to convert a smaller-diameter unipolar lead system to a larger connector block. Although this system allows a small-diameter lead to be used with a non-splittable catheter, this system has a disadvantage of not being adaptable for use with a bipolar leads.
Another example of an up-sizing adapter is disclosed in U.S. Pat. No. 4,583,543 issued to Peers-Trevarton. While this system is adaptable for use with bi-polar lead systems, it can only be used with a lead having a connector pin that is smaller than the connector bore. That is, it is not adaptable for use with a lead having a standard connector pin size but a non-standard connector body.
What is needed, therefore, is an improved system and method for allowing a lead connector of a first size to couple to a larger-sized device connector, and that addresses the foregoing problems.
The present invention is an improved connection system for coupling a device such as a pacemaker, cardioverter, defibrillator, nerve stimulator, muscle stimulator, implantable monitor or other device of the sort to a medical lead and which addresses the lead/device incompatibility issues discussed above while avoiding at least some of the drawbacks associated with conventional adapters or converters.
The current invention provides an up-sizing mechanism that may be used to size the proximal end of a lead to a predetermined convention such as the IS-1 standard. The system includes an up-sizing sleeve designed to couple to the proximal end of the lead, having a terminal connector pin conforming to a predetermined diameter, to a medical device. This up-sizing sleeve, which includes an internal surface forming a lumen sized to engage the proximal end of the lead and interior sealing rings to provide a fluid tight seal with the proximal end of the lead, may have one more relatively flexible and generally tubular members. The lead connector pin extends proximally beyond a proximal opening of the up-sizing sleeve, for a predetermined length, when the proximal end of the lead is engaged within the lumen of the up-sizing sleeve. Relatively rigid support members of the up-sizing sleeve prevent deformation of the sleeve, in order to maintain predetermined dimensions of an external surface of the sleeve when the proximal end of the lead is engaged within the lumen of the upsizing sleeve.
In another embodiment, the up-sizing sleeve includes a conductive ring member defining a means for electrically engaging to a ring connector on the proximal end of a lead. This means may include teeth for engaging the ring connector of the lead. Alternatively, the means may include a multi-beam connector or a spring coil. Furthermore, the conductive ring member of the up-sizing sleeve may be positioned between two relatively flexible and generally tubular members of the sleeve and include channels through which the two members are coupled. Additionally an alternative embodiment may include grommets, which serve as the interior sealing rings of the up-sizing sleeve, housed within the support members.
In additional embodiments many types of mechanical coupling mechanisms may be adapted to rigidly couple the up-sizing sleeve to the connector ring of the lead.
In a two-piece embodiment of the up-sizing sleeve, a first portion and second portion are adapted to come together in a snap fit. The conductive ring member is an integral part of the first portion, and the means for electrically engaging the connector ring of the proximal end of the lead is an integral part of the second portion. The means for electrical engagement is composed of deformable members adapted to slide under an edge of the conductive ring member for a snap fit within an inner surface of the conductive ring member.
In yet another embodiment of the current invention, one or more grooves may be formed in the proximal end of the lead and located to engage one or more positioning lips formed in the internal surface of the up-sizing sleeve when the proximal end of the lead is engaged within the lumen of the sleeve and the connector pin extends beyond a proximal opening of the sleeve for a predetermined length. Alternatively, the one or more grooves may engage one or more sealing rings of the up-sizing sleeve in a similar fashion.
In one embodiment, the up-sizing sleeve includes a reinforcing structure such as a coil. This reinforcing structure prevents the lead from flexing in a manner that results in lead failures. The coupling member may further include sealing rings on the exterior surface to provide a fluid-tight seal with the medical device, and/or sealing rings within the inner lumen to provide a fluid-tight seal with the lead body.
Because of the relatively tight press-fit formed between the up-sizing sleeve and the proximal end of the lead, one embodiment of the system includes a means to allow the lead to be more easily inserted within the inner lumen of the up-sizing sleeve. In one embodiment, the means to aid in insertion is a pull-wire device adapted to pull the proximal end of a medical electrical lead into the lumen of the up-sizing sleeve. Force applied to the pull wire pulls the lead body into the lumen of the sleeve until the connector pin extends proximally for a predetermined length beyond the proximal opening of the sleeve. In a second embodiment, the means to aid in insertion is a split tube that is inserted into a distal opening of the up-sizing sleeve. The proximal end of the lead is inserted into the lumen of the up-sizing sleeve via the split tube, which is then removed from around the lead body and extracted from the lumen of the up-sizing sleeve.
According to yet another embodiment of the current system, the up-sizing sleeve is bifurcated, having an offset leg to adapt the proximal end of a lead to more than one predetermined convention or standard. For example, the bifurcated up-sizing sleeve may conform to both a DF-1 and IS-1 standard.
The up-sizing system of the current invention provides a mechanism for up-sizing a lead having a non-standard proximal end terminated in a connector pin having a standard diameter. For example, the invention is particularly suited for small-diameter leads having an in-line connector pin. Unlike prior art designs, the up-sizing sleeve of the current invention allows the connector pin of the lead to be coupled directly to a medical device, while providing a means to up-size the proximal end of the lead body. Other advantages of the inventive connection system will become apparent to those skilled in the art from the drawings and accompanying description.